Dual Phase Steel with Improved Properties

ABSTRACT

A method for processing a dual phase steel sheet. The method includes heating the steel sheet to a first temperature (T 1 ), cooling the steel sheet to a second temperature (T 2 ), transitioning the steel sheet to a third temperature (T 3 ), and cooling the steel sheet to room temperature. T 1  is at least above the temperature at which the steel sheet transforms to austenite and ferrite. T 2  is below the martensite start temperature (M s ). The cooling rate to T 2  is sufficiently rapid to transform at least some austenite to martensite.

The present application claims priority from provisional patent application Ser. No. 62/103,286, entitled “Lean Dual Phase Steel with Improved Properties,” filed on Jan. 14, 2015. The disclosure of application Ser. No. 62/103,286 is incorporated herein by reference.

BACKGROUND

It is desirable to produce steels with high strength and good formability characteristics. The present invention relates to steel compositions and processing methods for production of steel using thermal processing techniques such that the resulting steel exhibits high strength and/or cold formability.

SUMMARY

The present steel is produced using a composition and a modified thermal process that together produces a resulting microstructure consisting of generally ferrite and a second phase generally comprising martensite and bainite (among other constituents). To achieve such a microstructure, the composition includes certain alloying additions and the thermal process includes a hot-dip galvanizing/galvannealing (HDG) or other thermal process with certain process modification.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate embodiments, and together with the general description given above, and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

FIG. 1 depicts a schematic view of a HDG temperature profile with a quenching step performed prior to galvanizing/galvannealing.

FIG. 2 depicts the HDG temperature profile of FIG. 1, with the average cooling rate of the HDG temperature profile shown in phantom.

FIG. 3 depicts a schematic view of an alternative HDG temperature profile with a quenching step performed after galvanizing/galvannealing.

DETAILED DESCRIPTION

FIG. 1 shows a schematic representation of a combination of a typical hot-dip galvanizing thermal profile and a modified hot-dip galvanizing thermal profile. The modified thermal cycle is used to achieve high strength and good formability in a dual phase steel sheet (described in greater detail below). In a steel sheet used with the two thermal cycles shown in FIG. 1, the steel sheet generally comprises two phases after the thermal cycles—a first phase of predominantly ferrite and a second phase. It should be understood that the term “second phase” used herein is generally used to refer to a phase generally comprising predominately martensite with some bainite. However, it should also be understood that such a second phase may also include any one or more of cementite and/or residual austenite. Additionally, it should be understood that while FIG. 1 is shown in connection with hot-dip galvanizing, in other embodiments a galvannealing or other hot-dip coating process can be used. In still other embodiments, hot-dip coating processes are omitted entirely and the steel sheet is merely subjected to the thermal profile as shown.

The solid line in FIG. 1 shows a schematic view of the typical hot-dip galvanizing or galvannealing thermal profile (10). As can be seen, the typical thermal profile (10) involves heating the steel sheet to a peak metal temperature (12) and optionally holding the steel sheet at the peak metal temperature (12) for a first predetermined period of time. In the present example, the peak metal temperature (12) is at least above the austenite transformation temperature (A₁) (e.g., dual phase austenite+ferrite region). Thus, at the peak metal temperature (12) at least a portion (by volume) of the steel will be transformed to a combination of austenite and ferrite. Although FIG. 1 shows that peak metal temperature as being solely above A₁, it should be understood that in some embodiments the peak metal temperature may also include temperatures above the temperature at which ferrite completely transforms to austenite (A₃) (e.g., the single phase, austenite region).

As stated above, in the typical thermal profile (10) the steel sheet is held at the peak metal temperature (12) for a first predetermined amount of time. It should be understood that the particular amount of time that the steel sheet is held at the peak metal temperature (12) may be varied by a number of factors such as the particular chemistry of the steel sheet, or the desired volumetric quantity of the second phase in the steel sheet at the conclusion of the thermal cycle. Additionally, in some circumstances the time held at the peak metal temperature (12) may be reduced to zero or near zero. In circumstances where the hold time is reduced, the peak metal temperature can be increased to compensate for such a reduction.

Once the first predetermined period of time has elapsed, the typical thermal profile (10) involves rapidly cooling the steel sheet to an intermediate temperature (14). The steel sheet is then held at the intermediate temperature (14) for a second predetermined period of time. Generally, the steel sheet is held at the intermediate temperature (14) for a sufficient amount of time to permit the steel sheet to reach a temperature that is near the temperature of the zinc bath.

Still referring to the typical thermal profile (10), the steel sheet is next inserted into a liquid zinc galvanizing tub or galvannealing apparatus. During this stage, the temperature of the steel sheet is slightly reduced to a bath temperature (16) that is below the intermediate temperature (14). The bath temperature (16) is generally below the intermediate temperature (14) to avoid dross formation upon entry of the steel sheet into the liquid zinc.

The steel sheet remains at the bath temperature (16) for the duration of the galvanizing Where galvannealing is used, the steel sheet is removed from the bath at some period of time and then elevated to an annealing temperature. The particular temperature of the bath temperature (16) is at least above the melting point of zinc (e.g., 419° C., 787° F.). However, it should be understood that in some examples the bath temperature (16) may be even higher depending on the particular configuration of the galvanizing bath or galvannealing apparatus. It should be also understood that in circumstances where the bath temperature (16) is higher relative to the melting point of zinc, the intermediate temperature (14) may remain the same as shown, be correspondingly raised, or even lowered.

At the conclusion of the galvanizing or galvanealing process, the steel sheet is cooled below the martensite start temperature (M_(s)), thereby transforming at least some austenite into martensite. Of course, as described above, other constituents may form such as bainite, pearlite, or retained austenite. These constituents, along with the formation of martensite, form what is collectively described herein as the second phase. As described above, although the second phase may contain one or more of martensite, bainite, pearlite and/or retained austenite, it should be understood that the second phase is generally characterized by formation of predominately martensite.

In some instances, modification to the typical thermal profile (10) described above is desirable. For example, because of the galvanizing or galvannealing step in the typical thermal profile (10), the average cooling rate from the peak metal temperature (12) to the martensite start temperature (M_(s)) may be insufficient to form a desirable volumetric quantity of martensite—instead forming non-martensitic transformation products (e.g., bainite, cementite, pearlite, and/or etc.). This may be the case regardless of how quickly the steel sheet is cooled after galvanizing or galvannealing. To account for this relatively slow average cooling rate, conventional dual phase steels used in such a process often includes high alloy content to increase hardenability and thereby avoid formation of non-martensitic transformation products. However, relatively high alloying additions may be undesirable due to increased cost and reduced mechanical properties. Thus, it can be desirable to modify the typical thermal profile (10) described above to maintain a desired amount of martensite in dual phase steels without high alloying additions. Further modifications described below, such as reheating from below the martensite start temperature (M_(s)) to the intermediate temperature (14), may additionally be desirable to improve mechanical properties such as hole expansion ratio (HER) or yield strength (regardless of the particular amount of alloying additions).

In the present embodiments of the modified thermal profile, improvements to the mechanical properties were more significant than expected, especially when considering the relatively short tempering time (e.g., duration of time during which the steel sheet is exposed to the zinc bath).

As shown in FIG. 1, the typical thermal profile (10) described above can be modified to include a quench step (18) prior to the galvanizing or galvannnealing step described above. As can be seen, this alternative procedure is generally identical to the procedure described above with the exception of the portion of the procedure related to the intermediate temperature (14). In particular, instead of quenching the steel sheet from the peak metal temperature (12) to the intermediate temperature (14), the steel sheet is quenched from the peak metal temperature (12) to a quench temperature (20). It should be understood that the cooling rate from the peak metal temperature (12) to the quench temperature (20) is generally high enough to transform at least some of the austenite formed at the peak metal temperature (12) to martensite. In other words, the cooling rate is rapid enough to transform austenite to martensite instead of other non-martensitic transformation products such as ferrite, pearlite, or bainite which form at relatively lower cooling rates.

In the present example, the quench temperature is below the martensite start temperature (M_(s)). The difference between the quench temperature (20) and the martensite start temperature (M_(s)) can vary depending on the individual composition of the steel sheet being used. However, in many embodiments the difference between quench temperature (20) and M_(s) is sufficiently great to form a predominately martensitic second phase.

Once the quench temperature (20) is reached, the temperature of the steel sheet is maintained at the quench temperature for a predetermined quench time. Because formation of martensite is nearly instantaneous, the particular amount of time during which the steel sheet is at the quench temperature is generally insignificant.

After quenching to the quench temperature (20), the steel sheet is reheated to the intermediate temperature (14) or to another temperature at or near the bath temperature (16). In the present example, reheating is relatively quick and may be performed using various methods such as induction heating, torch heating, and/or other methods known in the art. Once reheated, the steel sheet is inserted into a zinc bath. In the zinc bath, the steel sheet will reach the bath temperature (16), as described above, where the steel sheet will remain for the remainder of the galvanizing. The particular amount of time during which the steel sheet is in the zinc bath is largely determined by the galvanizing/galvannealing process. However, it should be understood that during this time, the martensite is tempered to thereby improve the mechanical properties of the steel sheet. Where a galvannealing process is used, the steel sheet may be heated to an annealing temperature after removal from the bath.

Although the reheating step is described herein as being in connection with a coating step, such as galvanizing or galvannealing, it should be understood that no such limitation is intended. For instance, in some examples the reheating step may merely be performed and then the process may proceed as described below. In such examples, the steel sheet is held at the intermediate temperature (14) or the bath temperature (16) despite not actually being subjected to a galvanizing or galvannealing treatment. Additionally, in some examples the steel sheet may be held at a lower temperature (e.g., 400° C.) relative to the bath temperature (16) because heating the steel sheet to the melting point of zinc is not necessary without application of zinc. The steel sheet may be held at such a temperature for any suitable time as will be apparent to those of ordinary skill in the art in view of the teachings herein.

Once the galvanizing, galvannealing, or other similar thermal process is completed, the steel sheet is cooled to room temperature, as similarly described above. Accordingly, in the present example, the steel sheet is first heated to a peak metal temperature (12) to form austenite and optionally ferrite. Next the steel sheet is cooled from the peak metal temperature (12) to the quench temperature (20) to form martensite or other constituents of the second phase. After quenching, the steel sheet is reheated to approximately the zinc bath temperature for galvanizing and optionally galvannealing. Finally, the steel sheet is cooled to ambient temperature.

FIG. 2 shows a comparison of the average cooling rate (30) of the typical thermal profile (10) versus the average cooling rate (32) of the typical thermal profile (10) modified to include the quench step (18). As can be seen, the quench step (18) substantially reduces the average cooling rate of the typical thermal profile (10). In examples where the method described herein is used in a continuous galvanizing/galvannealing line, average cooling rate may depend at least partially on the feed speed of the galvanizing/galvannealing line. For instance, where feed speeds of about 30 meters per minute are used, the average cooling rate using the typical thermal profile (10) is about 17° C. per second, while the average cooling rate using the modifications described herein is about 48° C. per second. In examples where feed speeds of about 91 meters per minute are used, the average cooling rate using the typical thermal profile (10) is about 6° C. per second, while the average cooling rate using the modifications described herein is about 16° C. per second. In yet other examples where feed speeds of about 120 meters per minute are used, the average cooling rate using the typical thermal profile (10) is about 4° C. per second, while the average cooling rate using the modifications described herein is about 12° C. per second.

Regardless of the particular cooling rate achieved, it should be understood that improved mechanical properties of the steel sheet can be achieved by reheating the steel sheet as described above. These improvements can be achieved whether the steel sheet includes conventional dual-phase alloy compositions or compositions with relatively low alloying elements described herein.

In embodiments where reduced cooling rates are achieved, it should be understood that because of the reduction in the average cooling rate, martensite is more readily formed when the quench step (18) is added to the typical thermal profile (10). Since the conditions increase the propensity to form martensite, less alloying elements are required in the steel sheet. Thus, when the quench step (18) is applied to the typical thermal profile (10) described above, dual phase steel can be galvanized or galvannealed with substantially less alloying elements. Despite having less alloying elements, the steel sheet can have similar post heat treatment martensite content as conventional dual phase steels treated using only the typical thermal profile (10).

It should be understood that in some examples it may be desirable to modify the typical thermal profile (10) such that the quench step (18) is performed after galvanizing/galvannealing instead of before. One such example can be seen in FIG. 3. In FIG. 3, the quench step (18) may be performed as similarly described above with a rapid cooling of the steel sheet below the martensite start temperature (M_(s)). When the quench step (18) is performed after galvanizing or galvannealing as shown in FIG. 3, the average cooling rate from the peak metal temperature (12) to the intermediate temperature (14) or bath temperature (16) is similar to the average cooling rate (30) for the typical thermal profile (10) shown in FIG. 2. Because this is a relatively low cooling rate, it should be understood that martensite formation will be reduced as similarly encountered in the typical thermal profile (10). With less martensite formation, higher alloying elements may be required to achieve desirable levels of martensite. Thus, applying the quench step (18) after galvanizing or galvannealing will not achieve cost savings associated with reduced alloying content. However, applying the quench step (18) after galvanizing or galvannealing will still nonetheless promote improved mechanical properties such as hole expansion ratio (HER) and yield strength. In some examples, these improvements to the mechanical properties of the steel sheet can be comparable to those improvements achieved through applying the quench step (18) prior to galvanizing or galvannealing.

In some variations of the process where the quench step (18) is applied after galvanizing or galvannealing, a tempering step (40) may also be performed, where the steel sheet is heated to a predetermined temperature above or below the martensite start temperature (M_(s)) for a predetermined period of time after the quench step (18). When such a tempering step is used, the average cooling rate is also similar to the average cooling rate (30) for the typical thermal profile (10) shown in FIG. 2. Thus, high alloy content will still be required to form a predominantly martensitic second phase. However, such a tempering step further improves mechanical properties such as hole expansion ratio (HER) and yield strength.

The steel sheet may include various alloying elements typically present in conventional dual phase steels. For instance, in some embodiments, carbon provides increased strength. For instance, increasing carbon concentration generally lowers the M_(s) temperature, lowers transformation temperatures for other non-martensitic constituents (e.g., bainite, ferrite, pearlite), and increases the time required for non-martensitic products to form. Additionally, increased carbon concentrations may improve the hardenability of the material thus retaining formation of non-martensitic constituents near the core of the material where cooling rates may be locally depressed. However, it should be understood that carbon additions may be limited as significant carbon concentrations can lead to detrimental effects on weldability. Furthermore, in greater concentrations carbon can have a detrimental effect of formability. Therefore, the carbon content is generally kept around 0.067-0.14 by weight.

In some embodiments manganese provides increased strength by lowering transformation temperatures of other non-martensitic constituents and increasing the amount of martensite. Manganese can further improve the propensity of the steel sheet to form martensite by increasing hardenability. Manganese can also increase strength through solid solution strengthening. However, the presence of manganese in large concentrations can degrade formability. Therefore the manganese content is generally present in the concentration of about 1.65-2.9 by weight.

In some embodiments aluminum additions are made to provide deoxidization. However, aluminum additions beyond certain levels can lead to formability being degraded. Accordingly, aluminum is generally present in the concentration of about 0.015-0.07 by weight.

In some embodiments silicon can be added to promote a dual phase structure consisting of predominately ferrite and martensite. However, when silicon is increased beyond certain concentrations, zinc will not adhere as effectively to the steel sheet. Accordingly, silicon is generally present in the concentration of about 0.1-0.25 by weight.

In some embodiments niobium is added to refine ferrite grains. Such grain refinement is desirable to improve formability and improve weld quality. However, if niobium concentrations exceed a certain amount, formability of the steel sheet will degrade. Accordingly, niobium is generally present in the concentration of about 0-0.045 by weight. Alternatively, in some examples niobium is present in the concentration of about 0.015-0.045 by weight.

In some embodiments vanadium is added to increase hardenability and/or refine ferrite grains. When added, vanadium is generally included in a concentration less than or equal to 0.05 by weight.

In some examples chromium is added to improve formability and weld quality. However, chromium additions exceeding certain concentrations will result in low quality surface properties. Accordingly, chromium may be included in the concentration of about 0-0.67, or 0.2-0.67 by weight.

In other embodiments molybdenum may be used to increase hardenability. When molybdenum is used, molybdenum can be included in a concentration of about 0.08-0.45 by weight. In other embodiments the lower limit concentration of molybdenum is reduced further, or even eliminated entirely.

In some embodiments titanium and boron are added to increase strength. It should be understood that in some embodiments titanium and boron may be used together, separately in lieu of the other, or neither element may be used. When titanium is used, titanium is present in the concentration of about 0.01-0.03 by weight. When boron is used, boron is present in the concentration of about 0.0007-0.0013 by weight.

In embodiments where titanium and boron are added together, titanium is generally present in suitable concentrations to substantially prevent boron from forming nitrides. Thus, titanium may be included to combine with nitrogen prior to the nitrogen combining with boron. In some circumstances titanium is included in concentrations of about 3.43 times the weight percent of nitrogen. When included in this concentration, titanium generally combines with nitrogen, thereby preventing boron from forming nitrides.

In other embodiments, variations in the concentrations of elements and the particular elements selected may be made. Of course, where such variations are made, it should be understood that such variations may have a desirable or undesirable effect on the steel sheet microstructure and/or mechanical properties in accordance with the properties described above for each given alloying addition.

Example 1

Embodiments of the steel sheet were made with the compositions set forth in Table 1 below.

TABLE 1 Chemical compositions in weight. Cast C Mn Al Si Nb V Code Min Max Min Max Min Max Min Max Min Max Min Max A 0.08 0.10 1.70 1.90 0.03 0.06 0.15 0.25 0.015 0.025 0.010 B 0.067 0.08 1.65 1.82 0.02 0.07 0.15 0.25 0.001 0.030 0.050 C 0.10 0.12 2.10 2.30 0.03 0.06 0.15 0.25 0.003 0.010 D 0.10 0.12 1.75 1.90 0.02 0.07 0.15 0.25 0.035 0.045 0.008 E 0.11 0.13 2.40 2.70 0.03 0.06 0.15 0.25 0.004 0.008 F 0.08 0.10 2.00 2.20 0.03 0.07 0.40 0.50 0.040 0.060 0.008 G 0.09 0.10 2.25 2.42 0.015 0.07 0.10 0.20 0.035 0.045 0.008 H 0.12 0.14 2.70 2.90 0.03 0.06 0.15 0.25 0.004 0.008 I 0.11 0.13 2.45 2.60 0.015 0.05 0.42 0.58 0.035 0.045 0.020 Cast Cr Mo Ti B Code Min Max Min Max Min Max Min Max A 0.20 0.30 0.02 0.01 0.03 0.001 B 0.16 0.20 0.01 0.02 0.001 C 0.20 0.30 0.25 0.35 0.003 0.001 D 0.20 0.30 0.15 0.20 0.01 0.020 0.001 E 0.30 0.40 0.35 0.45 0.005 0.0007 F 0.20 0.30 0.30 0.40 0.008 0.001 G 0.57 0.67 0.08 0.12 0.030 0.0007 0.0013 H 0.30 0.40 0.35 0.45 0.005 0.0007 I 0.57 0.63 0.05 0.015 0.025 0.0012 0.002

Example 2

Embodiments of the steel sheet made with the compositions set forth above in Table 1 were subjected to mechanical testing. Mechanical properties for a selected number of the compositions set forth in Table 1 are set forth below in Table 2.

TABLE 2 Mechanical properties for selected compositions of Table 1. Example of Alloy Quench Temperature YPE YS UTS TE HER Cast Code No. (° C.) ( ) (MPa) (MPa) ( ) ( ) Note D Not applicable 0 420 780 15 20 Comparative Example D 4 250 1.4 690 780 15 60 G Not applicable 0 650 980 11 20 Comparative Example F 6 250 1 840 980 13 50 I Not applicable 0 800 1180 8 — Comparative Example I 9 250 2.4 1120 1165 10 55

Example 3

Embodiments of the steel sheet were made with the compositions set forth in Table 3 below. The particular compositions shown in Table 3 are based on the compositional ranges set forth in Table 1.

TABLE 3 Chemical compositions in weight. Alloy Example of No. Cast Code Al B C Ca Cr Cu Mn Mo N Nb Ni 1 C w/o Mo 0.042 0.0005 0.094 <0.0003 0.25 <0.003 2.19 <0.003 0.0004 <0.003 <0.003 2 C 0.037 0.0004 0.093 <0.0003 0.25 <0.003 2.27 0.3 0.0005 <0.003 <0.003 3 D w/o Mo 0.041 0.0004 0.1 <0.0003 0.25 <0.003 1.86 <0.003 0.0012 0.042 <0.003 4 D 0.039 0.0004 0.1 <0.0003 0.25 <0.003 1.87 0.18 0.0011 0.042 <0.003 5 F w/o Mo 0.046 0.0004 0.087 <0.0003 0.25 <0.003 2.04 <0.003 0.001 0.053 <0.003 6 F 0.044 0.0004 0.086 <0.0003 0.25 <0.003 2.09 0.35 0.001 0.053 <0.003 7 G w/o Mo 0.037 0.0012 0.092 <0.0003 0.61 <0.003 2.24 <0.003 0.0004 0.04 <0.003 8 G 0.036 0.0013 0.091 <0.0003 0.61 <0.003 2.26 0.096 0.0004 0.043 <0.003 9 H w/o Mo 0.043 0.0006 0.13 <0.0003 0.35 <0.003 2.76 <0.003 0.0006 <0.003 <0.003 10 H 0.04 0.0005 0.13 <0.0003 0.34 <0.003 2.72 0.4 0.0008 <0.003 <0.003 11 I w/o Cr 0.029 0.0025 0.12 0.0003 <0.003 <0.003 2.47 <0.003 0.0008 0.042 <0.003 12 I 0.028 0.0026 0.12 0.0003 0.58 <0.003 2.48 <0.003 0.0011 0.045 <0.003 Alloy Example of No. Cast Code P S Si Sn Ti V 1 C w/o Mo <0.003 0.0004 0.19 <0.003 <0.003 <0.003 2 C 0.003 0.0006 0.18 <0.003 <0.003 <0.003 3 D w/o Mo <0.003 0.0004 0.2 <0.003 0.015 <0.003 4 D <0.003 0.0002 0.2 <0.003 0.015 <0.003 5 F w/o Mo <0.003 0.0005 0.43 <0.003 <0.003 <0.003 6 F <0.003 0.0005 0.43 <0.003 <0.003 <0.003 7 G w/o Mo <0.003 0.0005 0.14 <0.003 <0.003 <0.003 8 G <0.003 0.0004 0.15 <0.003 <0.003 <0.003 9 H w/o Mo <0.003 0.0004 0.19 <0.003 <0.003 <0.003 10 H <0.003 0.0004 0.19 <0.003 <0.003 <0.003 11 I w/o Cr <0.003 0.0004 0.49 <0.003 0.021 <0.003 12 I <0.003 0.0005 0.49 <0.003 0.021 <0.003

Example 4

Embodiments of the steel sheet made with the compositions set forth above in Table 3 were subjected to mechanical testing. Mechanical properties for each of the compositions set forth in Table 3 are set forth below in Tables 4 through 15.

TABLE 4 Mechanical properties for alloy no. 1 of Table 3. Time Time Time Tem- at Tem- at Tem- at EUL Uni- Hole pera- Tem- pera- Tem- pera- Tem- Stress form Total Expan- ture pera- ture pera- ture pera- @ 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE 0.5 OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) (MPa) (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 1 800 180 250 30 466 50 562 556 726 8 14 — 61 1 800 180 250 30 466 50 522 526 699 9 16 — 61 1 800 180 250 30 466 100 489 474 677 9 18 — 88 1 800 180 250 30 466 100 389 378 643 15 23 — 88 1 800 180 250 30 466 100 498 485 678 10 19 — 88 1 800 180 250 30 466 120 467 450 665 10 17 — 75 1 800 180 250 30 466 120 471 454 664 10 14 — 75 1 800 180 250 60 466 40 465 475 660 10 17 58 65 1 800 180 250 120 466 80 480 453 665 10 16 55 95 1 800 180 SKIP SKIP 466 50 392 384 649 14 22 — 55 Compar- ative 1 825 180 250 60 466 40 577 570 728 8 13 55 81 1 825 180 250 120 466 80 664 668 767 5 10 59 102 1 850 180 250 30 466 50 762 772 848 5 8 — 109 1 850 180 250 30 466 50 736 745 823 5 9 — 109 1 850 180 250 30 466 100 763 768 834 5 8 — 102 1 850 180 250 30 466 100 759 768 832 5 8 — 102 1 850 180 250 30 466 120 725 731 805 5 8 — 110 1 850 180 250 30 466 120 735 742 809 4 8 — 110 1 850 180 250 60 466 40 868 870 915 5 9 62 91 1 850 180 250 120 466 80 819 823 859 4 7 62 96

TABLE 5 Mechanical properties for alloy no. 2 of Table 3. Time Time Time Tem- at Tem- at Tem- at EUL Uni- Hole pera- Tem- pera- Tem- pera- Tem- Stress form Total Expan- ture pera- ture pera- ture pera- @ 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE 0.5 OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) (MPa) (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 2 800 180 250 30 466 50 577 584 811 9 15 — 49 2 800 180 250 30 466 50 575 581 813 9 16 — 49 2 800 180 250 30 466 100 623 628 855 8 14 — 21 2 800 180 250 30 466 100 583 583 836 8 14 — 21 2 800 180 250 30 466 120 484 474 850 9 14 — 32 2 800 180 250 30 466 120 435 418 843 10 15 — 32 2 800 180 250 60 466 40 673 687 849 7 9 62 27 2 800 180 250 120 466 80 678 684 857 8 14 62 56 2 800 180 SKIP SKIP 466 50 469 457 843 10 16 — 24 Compara 2 800 180 SKIP SKIP 466 50 459 453 829 10 16 — 24 Compara 2 825 180 250 60 466 40 716 726 855 6 10 63 83 2 825 180 250 120 466 80 815 824 891 6 11 63 92 2 850 180 250 30 466 50 891 914 990 5 7 — 86 2 850 180 250 30 466 50 878 901 975 5 9 — 86 2 850 180 250 30 466 100 845 864 938 4 7 — 106 2 850 180 250 30 466 100 836 863 940 4 7 — 106 2 850 180 250 30 466 120 843 866 943 4 7 — 93 2 850 180 250 30 466 120 828 845 931 4 8 — 93 2 850 180 250 60 466 40 977 971 0 969 973 1007 5 9 64 78 2 850 180 250 120 466 80 951 946 0 949 946 978 5 9 64 104

TABLE 6 Mechanical properties for alloy no. 3 of Table 3. Time Time Time Tem- at Tem- at Tem- at EUL Uni- Hole pera- Tem- pera- Tem- pera- Tem- Stress form Total Expan- ture pera- ture pera- ture pera- @ 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE 0.5 OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) (MPa) (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 3 800 180 250 30 466 50 606 606 764 9 15 — 51 3 800 180 250 30 466 50 595 595 756 10 15 — 51 3 800 180 250 30 466 100 626 628 765 9 13 — 53 3 800 180 250 30 466 100 609 609 752 8 12 — 53 3 800 180 250 30 466 120 625 625 766 9 12 — 43 3 800 180 250 30 466 120 593 595 746 9 13 — 43 3 800 180 250 60 466 40 619 612 1 613 612 760 10 16 60 52 3 800 180 250 120 466 80 622 616 1 616 618 745 10 17 59 52 3 800 180 SKIP SKIP 466 50 561 559 748 11 15 — 37 Compara 3 800 180 SKIP SKIP 466 50 579 578 758 11 15 — 37 Compara 3 825 180 250 60 466 40 582 572 1 575 574 732 12 18 59 69 3 825 180 250 120 466 80 576 568 1 568 570 711 11 18 59 70 3 850 180 250 30 466 50 679.2 678.7 0.44 672 674 770 8 12 — 66 3 850 180 250 30 466 50 668.7 663 0.4 667 665 760 9 14 — 66 3 850 180 250 30 466 100 669.2 651 1.47 658 658 744 9 14 — 67 3 850 180 250 30 466 100 626.5 620.3 0.73 621 621 728 9 14 — 67 3 850 180 250 30 466 120 681.9 655.6 1.93 656 657 739 9 13 — 85 3 850 180 250 30 466 120 654.1 637.9 2.22 638 640 733 8 13 — 85 3 850 180 250 60 466 40 649 608 3 609 610 698 12 22 59 78 3 850 180 250 120 466 80 624 594 2 595 595 697 12 20 58 84 3 850 180 SKIP SKIP 466 50 580.2 577.4 0.7 580 580 706 12 18 — 89 Compara 3 850 180 SKIP SKIP 466 50 556 556 697 12 20 — 89 Compara

TABLE 7 Mechanical properties for alloy no. 4 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 4 800 180 250 30 466 50 711 724 866 7 10 — 36 4 800 180 250 30 466 50 698 713 855 8 12 — 36 4 800 180 250 30 466 100 721 734 860 6 7 — 63 4 800 180 250 30 466 100 717 728 857 5 7 — 63 4 800 180 250 30 466 120 713 722 863 8 12 — 43 4 800 180 250 30 466 120 702 707 845 9 12 — 43 4 800 180 250 60 466 40 705 706 854 8 14 59 34 4 800 180 250 120 466 80 755 765 877 7 12 62 53 4 800 180 SKIP SKIP 466 50 609 615 841 9 14 — 35 Compara 4 800 180 SKIP SKIP 466 50 606 608 839 10 15 — 35 Compara 4 825 180 250 60 466 40 689 693 820 9 13 60 57 4 825 180 250 120 466 80 679 679 819 9 15 63 69 4 850 180 250 30 466 50 720.5 719. 0.1 719 720 814 8 13 — 53 4 850 180 250 30 466 50 722 726 824 7 11 — 53 4 850 180 250 30 466 100 705.5 701 0.2 704 705 799 8 12 — 62 4 850 180 250 30 466 100 710.5 708 0.0 708 710 804 7 10 — 62 4 850 180 250 30 466 120 720.8 709. 0.0 710 710 796 8 12 — 94 4 850 180 250 30 466 120 689.6 688. 0.0 689 690 779 8 12 — 94 4 850 180 250 60 466 40 717 694 1 695 695 785 9 15 59 65 4 850 180 250 120 466 80 695 675 1 682 682 779 9 15 58 58 4 850 180 SKIP SKIP 466 50 626 628 775 10 16 — 63 Compara 4 850 180 SKIP SKIP 466 50 624 625 771 10 14 — 63 Compara

TABLE 8 Mechanical properties for alloy no. 5 of TABLE 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 5 800 180 250 30 466 50 559.2 557. 0.6 561 560 782 12 17 — — 5 800 180 250 30 466 50 579.7 579. 0.2 580 580 803 11 16 — — 5 800 180 250 30 466 100 575.9 575. 0.2 572 571 803 11 17 — 28 5 800 180 250 30 466 100 613 612. 0.3 607 607 810 10 14 — 28 5 800 180 250 30 466 120 565.3 560. 0.8 567 567 785 11 17 — 36 5 800 180 250 30 466 120 551.1 550. 0.7 557 556 805 10 15 — 36 5 800 180 250 60 466 40 574 572 1 575 576 788 11 16 60 32 5 800 180 250 120 466 80 634 634 830 10 15 59 40 5 800 180 SKIP SKIP 466 50 493 490 805 11 16 — 34 Compara 5 800 180 SKIP SKIP 466 50 499 495 788 11 16 — 34 Compara 5 825 180 250 60 466 40 536 536 735 13 18 58 55 5 825 180 250 120 466 80 541 535 1 538 537 734 11 18 56 55 5 850 180 250 30 466 50 650.7 626. 0.4 628 628 755 11 17 — 51 5 850 180 250 30 466 50 559.3 551. 1.6 553 552 735 12 17 — 51 5 850 180 250 30 466 100 581.7 579. 0.5 580 580 760 11 16 — 66 5 850 180 250 30 466 100 563 562 0.9 563 563 735 11 17 — 66 5 850 180 250 30 466 120 609.1 597. 1.3 599 599 757 12 18 — 61 5 850 180 250 30 466 120 590.4 565. 1.2 586 586 737 11 19 — 61 5 850 180 250 60 466 40 593 580 1 585 584 731 13 19 57 64 5 850 180 250 60 466 40 593 580 1 585 584 731 13 19 57 64 5 850 180 250 120 466 80 564 553 1 553 553 716 12 20 56 49

TABLE 9 Mechanical properties for alloy no. 6 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 6 800 180 250 30 466 50 593 592 964 8 12 — 30 6 800 180 250 30 466 50 604 603 975 8 12 — 30 6 800 180 250 30 466 100 557 552 995 8 12 — 24 6 800 180 250 30 466 100 554 548 991 8 11 — 24 6 800 180 250 30 466 120 551 547 972 8 14 — 23 6 800 180 250 30 466 120 559 556 983 8 13 — 23 6 800 180 250 60 466 40 793 791 1 793 798 997 8 13 67 23 6 800 180 250 120 466 80 741 739 0 739 739 987 8 13 65 33 6 800 180 SKIP SKIP 466 50 598 613 1003 7 13 — 24 Compara 6 800 180 SKIP SKIP 466 50 602 618 1002 7 12 — 24 Compara 6 825 180 250 60 466 40 814 812 0 814 815 989 8 12 64 46 6 825 180 250 120 466 80 885 866 2 879 866 964 9 14 65 53 6 850 180 250 30 466 50 731.1 710. 1.2 714 715 873 9 16 — 36 6 850 180 250 30 466 50 724.6 718 1.2 725 725 874 10 16 — 36 6 850 180 250 30 466 100 685.6 682. 0.8 694 696 899 9 13 — 50 6 850 180 250 30 466 100 693.8 693 1.0 702 703 899 8 14 — 50 6 850 180 250 30 466 120 720.6 702. 1.2 706 707 892 9 16 — 43 6 850 180 250 30 466 120 715.3 706. 1.3 708 708 889 9 15 — 43 6 850 180 250 60 466 40 792 762 1 782 767 878 9 15 64 62 6 850 180 250 120 466 80 807 776 2 782 786 893 9 15 62 58

TABLE 10 Mechanical properties for alloy no. 7 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 7 800 180 250 30 466 50 688 697 929 8 12 — 36 7 800 180 250 30 466 50 697 709 941 8 12 — 36 7 800 180 250 30 466 100 666 678 915 6 9 — 41 7 800 180 250 30 466 100 719 733 936 7 7 — 41 7 800 180 250 30 466 120 567 566 928 8 11 — 32 7 800 180 250 30 466 120 563 563 918 8 11 — 32 7 800 180 250 60 466 40 655 653 0 637 638 919 9 13 64 32 7 800 180 250 120 466 80 797 790 1 792 791 956 8 13 62 37 7 800 180 SKIP SKIP 466 50 542 550 938 9 14 — 30 Compara 7 800 180 SKIP SKIP 466 50 553 562 950 8 11 — 30 Compara 7 825 180 250 60 466 40 704 702 1 705 704 904 9 15 65 48 7 825 180 250 120 466 80 773 760 1 763 763 895 8 13 62 63 7 850 180 250 30 466 50 1031. 1031 0.0 940 1031 1074 4 6 — 58 7 850 180 250 30 466 50 1041. 1040 0.1 951 1040 1076 3 5 — 58 7 850 180 250 30 466 100 1003. 1000 0.0 926 1004 1053 4 6 — 64 7 850 180 250 30 466 100 1035. 1030 0.7 940 1032 1067 5 6 — 64 7 850 180 250 30 466 120 948.8 947. 0.1 904 948 1016 5 8 — 58 7 850 180 250 30 466 120 953.3 953. 0.1 913 953 1019 5 6 — 58 7 850 180 250 60 466 40 979 948 0 970 951 979 1 8 67 64 7 850 180 250 120 466 80 1032 988 0 984 992 1032 1 9 65 58 7 850 180 SKIP SKIP 466 50 675 697 927 7 12 — 55 Compara 7 850 180 SKIP SKIP 466 50 666 691 911 7 12 — 55 Compara

TABLE 11 Mechanical properties for alloy no. 8 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 8 800 180 250 30 466 50 731 750 978 8 12 — 35 8 800 180 250 30 466 50 753 783 982 6 11 — 35 8 800 180 250 30 466 100 739 762 970 6 9 — 42 8 800 180 250 30 466 100 733 754 966 5 5 — 42 8 800 180 250 30 466 120 557 554 970 8 10 — 37 8 800 180 250 30 466 120 549 546 960 8 10 — 37 8 800 180 250 60 466 40 766 764 1 767 773 960 8 12 64 39 8 800 180 250 120 466 80 867 852 1 863 856 987 8 13 66 34 8 800 180 SKIP SKIP 466 50 1008. 1007 0.0 945 1008 1069 5 8 — 28 Compara 8 800 180 SKIP SKIP 466 50 579 601 994 8 12 — 28 Compara 8 825 180 250 60 466 40 860 849 1 852 855 975 8 12 66 52 8 825 180 250 120 466 80 875 854 1 872 852 931 7 11 63 62 8 850 180 250 30 466 50 999.9 131. 0.0 930 1007 1048 3 5 — 58 8 850 180 250 30 466 50 948 1024 1071 3 6 — 58 8 850 180 250 30 466 100 937 1006 1063 3 6 — 49 8 850 180 250 30 466 100 889 932 1005 5 8 — 49 8 850 180 250 30 466 120 579 610 1003 7 11 — 69 8 850 180 250 30 466 120 897 965 1034 4 6 — 69 8 850 180 250 60 466 40 1090 1037 0 103 1048 1090 1 7 66 66 8 850 180 250 120 466 80 1068 1022 0 100 1029 1068 1 9 64 89 8 850 180 SKIP SKIP 466 50 648 692 931 7 11 — 55 Compara 8 850 180 SKIP SKIP 466 50 667 688 939 7 11 — 55 Compara

TABLE 12 Mechanical properties for alloy no. 9 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 9 800 180 250 30 466 50 867 913 1040 6 9 — — 9 800 180 250 30 466 50 870 937 1042 6 9 — — 9 800 180 250 30 466 100 800 835 1001 7 10 — — 9 800 180 250 30 466 100 800 846 997 7 11 — — 9 800 180 250 30 466 120 847 884 1015 6 9 — — 9 800 180 250 30 466 120 879 911 1015 6 10 — — 9 800 180 250 60 466 40 890 923 998 6 9 65 58 9 800 180 250 120 466 80 816 839 969 7 11 64 63 9 800 180 SKIP SKIP 466 50 543 543 958 9 15 — — Compara 9 825 180 250 60 466 40 968 998 1046 5 8 69 71 9 825 180 250 120 466 80 1008 100 0 985 1003 1028 5 9 67 53 9 850 180 250 30 466 50 870 932 1043 6 8 — — 9 850 180 250 30 466 50 863 913 1038 6 9 — — 9 850 180 250 30 466 100 894 936 1042 5 8 — — 9 850 180 250 30 466 100 882 923 1039 6 10 — — 9 850 180 250 30 466 120 758 817 1121 6 10 — — 9 850 180 250 30 466 120 844 887 1011 6 10 — — 9 850 180 250 30 466 120 537 542 955 9 14 — — 9 850 180 250 60 466 40 989 1006 1045 5 9 64 54 9 850 180 250 120 466 80 1000 998 0 990 998 1040 5 9 64 71

TABLE 13 Mechanical properties for alloy no. 10 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 10 800 180 250 30 466 50 845 911 1150 6 9 — — 10 800 180 250 30 466 50 831 899 1148 6 9 — — 10 800 180 250 30 466 100 710 735 1137 7 10 — — 10 800 180 250 30 466 100 727 755 1132 7 10 — — 10 800 180 250 30 466 120 820 860 1147 7 10 — — 10 800 180 250 30 466 120 762 796 1138 7 9 — — 10 800 180 250 60 466 40 1019 101 1 974 1017 1139 7 11 68 34 10 800 180 250 120 466 80 928 923 1 927 928 1132 8 12 68 43 10 800 180 SKIP SKIP 466 50 666 711 1158 6 11 — — Compara 10 800 180 SKIP SKIP 466 50 648 684 1134 6 9 — — Compara 10 825 180 250 60 466 40 1089 107 1 101 1081 1149 6 11 68 41 10 825 180 250 120 466 80 1077 106 1 101 1069 1125 6 10 69 41 10 850 180 250 30 466 50 825 885 1125 6 9 — — 10 850 180 250 30 466 50 839 900 1126 6 9 — — 10 850 180 250 30 466 100 861 918 1129 6 9 — — 10 850 180 250 30 466 100 855 909 1118 6 9 — — 10 850 180 250 30 466 120 730 796 1130 6 9 — — 10 850 180 250 60 466 40 100 1057 1120 6 9 68 48 10 850 180 250 120 466 80 993 1040 1113 6 9 65 49

TABLE 14 Mechanical properties for alloy no. 11 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 11 800 180 250 30 466 50 692 706 1047 8 12 — 26 11 800 180 250 30 466 50 667 676 1037 9 12 — 26 11 800 180 250 30 466 100 719 751 1027 7 9 — 31 11 800 180 250 30 466 100 714 738 1021 7 7 — 31 11 800 180 250 30 466 120 608 611 1041 9 12 — 28 11 800 180 250 30 466 120 621 623 1056 10 14 — 28 11 800 180 250 60 466 40 727 731 1042 9 14 64 26 11 800 180 250 120 466 80 769 776 1085 9 13 68 28 11 800 180 SKIP SKIP 466 50 590 599 1070 9 12 — 26 Compara 11 800 180 SKIP SKIP 466 50 582 602 1060 9 12 — 26 Compara 11 825 180 250 60 466 40 778 768 1 775 777 1029 9 13 63 36 11 825 180 250 120 466 80 820 807 1 820 809 995 9 15 61 36 11 850 180 250 30 466 50 1094. 173. 0.0 940 1094 1132 6 8 — 40 11 850 180 250 30 466 50 958 1112 1141 3 9 — 40 11 850 180 250 30 466 100 1048. 1047 0.0 893 1048 1105 6 8 — 44 11 850 180 250 30 466 100 1075. 151. 0.0 907 1071 1127 5 9 — 44 11 850 180 250 30 466 120 907 1037 1114 6 9 — 45 11 850 180 250 30 466 120 894 1011 1107 6 9 — 45 11 850 180 250 60 466 40 104 1100 1162 1 5 67 42 11 850 180 250 120 466 80 103 1072 1130 1 5 67 81 11 850 180 SKIP SKIP 466 50 668 720 1047 7 10 — 35 Compara 11 850 180 SKIP SKIP 466 50 675 712 1046 7 11 — 35 Compara

TABLE 15 Mechanical properties for alloy no. 12 of Table 3. Time Time Time Tem- at Tem- at Tem- at Uni- Hole pera- Tem- pera- Tem- pera- Tem- EUL form Total Expan- ture pera- ture pera- ture pera- Stress 0.2 Elonga- Elonga- Hard- sion Alloy 1 ture 2 ture 3 ture UYS LYS YPE @ OYS UTS tion tion ness Ratio No. (° C.) 1 (s) (° C.) 2 (s) (° C.) 3 (s) (MPa) (MPa) ( ) 0.5 (MPa) (MPa) ( ) ( ) (HRA) ( ) Note 12 800 180 250 30 466 50 650 687 1194 7 10 — 21 12 800 180 250 30 466 50 660 698 1188 7 9 — 21 12 800 180 250 30 466 100 770 815 1136 8 11 — 23 12 800 180 250 30 466 100 897 924 1138 8 10 — 23 12 800 180 250 30 466 120 641 693 1171 8 11 — 23 12 800 180 250 30 466 120 656 710 1176 6 9 — 23 12 800 180 250 60 466 40 811 819 1169 8 12 67 26 12 800 180 250 120 466 80 760 766 1168 8 12 67 25 12 800 180 SKIP SKIP 466 50 661 720 1205 7 10 — 20 Compara 12 800 180 SKIP SKIP 466 50 676 738 1225 7 10 — 20 Compara 12 825 180 250 60 466 40 849 846 1 852 856 1153 8 13 66 50 12 825 180 250 120 466 80 1080 103 2 100 1038 1133 7 12 67 41 12 850 180 250 30 466 50 913 1072 1196 7 10 — 30 12 850 180 250 30 466 50 934 1102 1199 6 10 — 30 12 850 180 250 30 466 100 912 1080 1192 7 9 — 32 12 850 180 250 30 466 100 943 1109 1199 7 9 — 32 12 850 180 250 30 466 120 837 954 1186 7 10 — 34 12 850 180 250 30 466 120 829 956 1181 7 9 — 34 12 850 180 250 60 466 40 1177 113 3 104 1141 1178 7 11 68 49 12 850 180 250 120 466 80 1133 108 2 105 1098 1152 7 10 66 60 12 850 180 SKIP SKIP 466 50 727 831 1206 6 10 — 35 Compara 12 850 180 SKIP SKIP 466 50 736 868 1230 6 10 — 35 Compara

It will be understood various modifications may be made to this invention without departing from the spirit and scope of it. Therefore, the limits of this invention should be determined from the appended claims. 

What is claimed is:
 1. A method for processing a dual phase steel sheet, the method comprising: (a) heating the steel sheet to a first temperature (T1), wherein T1 is at least above the temperature at which the steel sheet transforms to austenite and ferrite to form at least some austenite in the steel sheet; (b) cooling the steel sheet to a second temperature (T2) by cooling at a cooling rate, wherein T2 is below the martensite start temperature (M_(s)), wherein the cooling rate is sufficiently rapid to transform at least some the austenite to martensite; (c) transitioning the steel sheet to a third temperature (T3); and (e) cooling the steel sheet to room temperature.
 2. The method of claim 1, further comprising hot dip galvanizing or galvannealing the steel sheet after the steel sheet is transitioned to T3.
 3. The method of claim 1, wherein the hot dip galvanizing or galvannealing occurs above M_(s).
 4. The method of claim 1, wherein the step of cooling the steel sheet to T2 is performed prior to the step of transitioning the steel sheet to T3.
 5. The method of claim 4, wherein the step of transitioning the steel sheet to T3 includes reheating the steel sheet from T2 to T3.
 6. The method of claim 1, wherein the step of cooling the steel sheet to T2 is performed after the step of transitioning the steel sheet to T3.
 7. The method of claim 1, wherein the step of cooling the steel sheet to T2 is sufficiently rapid to transform substantially all austenite to martensite.
 8. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.080-0.1 carbon; 1.7-1.9 manganese; 0.15-0.25 silicon; 0.02 or less molybdenum; 0.015-0.025 niobium; 0.2-0.3 chromium; and the balance being iron and other incidental impurities.
 9. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.067-0.080 carbon; 1.65-1.82 manganese; 0.15-0.25 silicon; 0.16-0.02 molybdenum; 0.001 or less niobium; and the balance being iron and other incidental impurities.
 10. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.10-0.12 carbon; 2.1-2.3 manganese; 0.15-0.25 silicon; 0.003 or less niobium; 0.2-0.3 chromium; and the balance being iron and other incidental impurities.
 11. The method of claim 10, wherein the steel sheet further comprises 0.25-0.35 molybdenum.
 12. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.10-0.12 carbon; 1.75-1.9 manganese; 0.15-0.25 silicon; 0.035-0.045 niobium; 0.2-0.3 chromium; and the balance being iron and other incidental impurities.
 13. The method of claim 12, wherein the steel sheet further comprises 0.15-0.2 molybdenum.
 14. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.11-0.13 carbon; 2.4-2.7 manganese; 0.15-0.25 silicon; 0.35-0.45 molybdenum; 0.004 or less niobium; 0.3-0.4 chromium; and the balance being iron and other incidental impurities.
 15. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.80-0.10 carbon; 2.0-2.2 manganese; 0.40-0.50 silicon; 0.04-0.060 niobium; 0.2-0.3 chromium; and the balance being iron and other incidental impurities.
 16. The method of claim 15, wherein the steel sheet further comprises 0.30-0.40 molybdenum.
 17. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.09-0.10 carbon; 2.25-2.42 manganese; 0.10-0.20 silicon; 0.035-0.045 niobium; 0.57-0.67 chromium; and the balance being iron and other incidental impurities.
 18. The method of claim 17, wherein the steel sheet further comprises 0.08-0.12 molybdenum.
 19. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.12-0.14 carbon; 2.7-2.9 manganese; 0.15-0.25 silicon; 0.004 or less niobium; 0.3-0.4 chromium; and the balance being iron and other incidental impurities.
 20. The method of claim 19, wherein the steel sheet further comprises 0.35-0.45 molybdenum.
 21. The method of claim 1, wherein the steel sheet comprises the following elements by weight percent: 0.11-0.13 carbon; 2.45-2.60 manganese; 0.420-0.580 silicon; 0.05 or less molybdenum; 0.035-0.045 niobium; and the balance being iron and other incidental impurities.
 22. The method of claim 21, wherein the steel sheet further comprises 0.57-0.63 chromium. 